A Practical Guide to Calculating Cohen’s f2, a Measure of Local Effect Size, from PROC MIXED

Reporting effect sizes in scientific articles is increasingly widespread and encouraged by journals; however, choosing an effect size for analyses such as mixed-effects regression modeling and hierarchical linear modeling can be difficult. One relatively uncommon, but very informative, standardized measure of effect size is Cohen's f(2), which allows an evaluation of local effect size, i.e., one variable's effect size within the context of a multivariate regression model. Unfortunately, this measure is often not readily accessible from commonly used software for repeated-measures or hierarchical data analysis. In this guide, we illustrate how to extract Cohen's f(2) for two variables within a mixed-effects…

• UO
  University of Pennsylvania
• PS
  Pennsylvania State University

  Award: P50 DA010075
• NI
  National Institute on Drug Abuse

  Awards: R01 DA022313 A2, R21 DA029834, P50 DA010075, R01 DA022313 S1, R21 DA029834-01
• NC
  National Cancer Institute

  Awards: P01 CA098262, CA098262